When I come across an item I'd like to get but which is over priced I usually respond by saying something to the extent of...
Hello - If you don't get your price and decide to review that please let me know.
I'll hear from the seller about half the time.
As for those "make offer" CL listings that don't state a price - they're liable to get flagged. I'm not sure if it's a violation of CL's terms of service or not but back when I posted some things for sale like that - "Make offer" - and they got flagged off because I didn't state a price - which could then be "or best offer". I was advised that they don't allow you to run auctions on CL.
At any rate - if no price is listed I'll reply and state my interest in the item and ask the seller to state the price he'd be willing to take.
Just what I do...not Gospel :-)